The study of the localization of iron within the brain has been expanded to include experiments on the effects of dietary iron deficiency on brain iron and others involving x-ray elemental analysis of brain tissue. A completed pilot study has established the techniques for inducing dietary iron deficiency, obtaining blood samples, and measuring hemoglobin; the Perls'+DAB histochemical test for iron has been modified for very low levels of iron. X-ray elemental analysis with electron beam imaging and microspectroscopy at the Biological Engineering and Instrumentation Branch, DRS, permits the quantification of iron within individual brain cells and perhaps also within structures as small as organelles. In addition, other metals in association with the iron deposits can be detected. This method can be used to verify the identification of iron accumulations made with the DAB intensification of the Perls' histochemical method for ferric iron.